This invention relates to an electrostatographic printing machine, and more particularly concerns a printing machine arranged to reproduce a plurality of transparencies and at least one opaque original document in an ordered sequence.
An electrostatographic printing process involves the formation and utilization of electrostatic latent charge patterns for the purpose of recording and reproducing the patterns in viewable form. The field of electrostatographic printing includes electrographic and electrophotographic printing. Electrophotographic printing is that class of electrostatographic printing which employs a photosensitive medium to form, with the aid of electromagnetic radiation, the electrostatic latent charge pattern. Xerography, which employs infra-red, visible or ultraviolet radiation and xero-radiography are sub-classes of electrophotography. Electrography is that class of electrostatography which utilizes an insulating medium to form, without the aid of electromagnetic radiation, the electrostatic latent charge pattern. Xero-printing which uses the pattern of insulating material on a conductive medium to form electrostatic charge patterns and electrographic recording, which uses a charge transfer between the plurality of electrodes to form directly electrostatic charge patterns, are sub-classes of electrographic printing. In all of the foregoing types of machines, it is highly desirable to be capable of reproducing transparencies as well as opaque original documents. More particularly, it is highly advantageous to provide a plurality of transparencies in an ordered sequence with each transparency being reproduced sequentially so as to produce a set of collated copies. However, it is further advantageous to be capable of interposing selectively opaque original documents within the ordered set of transparencies so as to produce a plurality of sets of copies comprising an ordered arrangement of the transparencies and opaque original documents.
The process of electrophotographic printing will be described hereinafter as an exemplary system for achieving the foregoing. An electrophotographic printing machine exposes a charged photoconductive member to a light image of the transparency or opaque original document being reproduced. The irradiated areas of the photoconductive surface are discharged recording thereon an electrostatic latent image corresponding to the informational areas contained within the transparency or opaque original document. A development system moves a developer mix with carrier granules and toner particles into contact with the photoconductive surface. The toner particles are attracted electrostatically from the carrier granules to the latent image forming a toner powder image thereon. Thereafter, the toner powder image is transferred to a sheet of support material. After transferring the toner powder image from the latent image to the sheet of support material, a fusing device permanently affixes the the toner powder image thereto. The foregoing briefly describes the basic operation of an electrophotographic printing machine. This concept was originally disclosed by Carlson in U.S. Pat. No. 2,297,691 and is further amplified and described by many related patents in the art.
Many special purpose electrophotographic printing machines have been developed and are in wide commercial use. For example, electrophotographic printing machines are presently commercially available for reproducing microfilm. Machines of this type are described in U.S. Pat. No. 3,424,525 issued to Towers et al in 1969; U.S. Pat. No. 3,542,468 issued to Blow, Jr. in 1970; and U.S. Pat. No. 3,547,533 issued to Stokes et al in 1970. In general, a microfilm reproducing machine produces an enlarged copy of a microfilm original. However, high quality reproduction of color slides has also recently been achieved. This process is exemplified by co-pending application Ser. No. 540,617 filed in 1975, and co-pending application Ser. No. 663,389 filed in 1976. As disclosed in the foregoing applications, a light image of a color transparency is projected onto a mirror. The mirror reflects the light image through a screen and field lens onto the charged portion of the photoconductive surface. This light image is filtered to record a single color electrostatic latent image on the photoconductive surface. Successive single color electrostatic latent images are recorded and developed with appropriately colored toner particles. These toner powder images are transferred to a sheet of support material, in superimposed registration with one another. This multi-layer toner powder image is then permanently affixed to the sheet of support material forming a copy of the color slide being reproduced. Improvements in this basic process include positioning a mirror in the path of the transparency light image to direct the light image onto the charged portion of the photoconductive member with the mirror being readily removable from the optical light path so as to reproduce opaque original documents. More recently, it has been found that a ordered set of slides may be reproduced as a plurality of sets of ordered copies. The foregoing is more fully described in co-pending application Ser. No. 701,447 filed in 1976. As disclosed therein, a set of slides is disposed in a slide projector, in an ordered sequence, and automatically indexed to form a plurality of collated sets of copies. However, it is also extremely desirable to be capable of reproducing ordered sets of slides having copies of opaque original documents interleafed therebetween.
Accordingly, it is a primary object of the present invention to improve electrostatographic printing machines by reproducing sets of collated copies from an ordered arrangement of transparencies and opaque original documents.